Fifty years ago today, Martin Luther King Jr. penned one of the most enduring documents of the civil-rights struggle while locked in a jail cell in Birmingham, Ala.

His Letter From Birmingham Jail was a clarion call for the right to civil disobedience. Though first requested by an editor for The New York Times, it was in the pages of The New York Post that these words would first be printed.

This week, the Times published a very different kind of prison letter. Yesterday its op-ed pages carried an article titled “Gitmo Is Killing Me.” It was written by Samir Naji al Hasan Moqbel, whom the Times identifies only as “a prisoner at Guantanamo Bay since 2002.”

In his piece, Moqbel complains about being force-fed (he says he’s on hunger strike) and claims the accusations against him are “nonsense, like something out of the American movies I used to watch.”

He insists: “No one seriously thinks I am a threat.”

Pity the Times didn’t take a look at its own Web site before publishing. There, under a project called “The Guantanamo Docket,” is a Defense Department memo identifying the Yemeni national as “a member of al Qaeda who served on Osama bin Laden’s security detail.”

The memo goes on to say Moqbel “admitted fighting on the front lines” and was captured by Pakistani forces along with “31 other Arab al Qaeda fighters,” including the 20th 9/11 hijacker. As for no one seriously believing Moqbel a threat, the Pentagon calls him “A HIGH RISK . . . as he is likely to pose a threat to US interests.”

In a week that marks the 50th anniversary of the Rev. King’s letter as well as a new terror attack on Boston, we suspect the Times made history — but probably not the way it intended.